Hydrocarbon conversion



United States Patent 3,265,612 HYDROCARBON CONVERSION Clarence L. Dulaney and Marvin Lee Owens, Jr., Texas City, Tex., assignors to Monsanto Company, a corporation of Delaware No Drawing. Filed Mar. 20, 1963, Ser. No. 266,520

5 Claims. (Cl. 208130) v The present invention relates to a process for the thermal cracking of hydrocarbons. Further, the present invention relates to a process for the production of aromatic hydrocarbons. vention relates to a process for the thermal cracking of paraffinic hydrocarbons to obtain a cracked product of increased aromatic hydrocarbon content. 1

Because of the relatively low economic value of parafiin hydrocarbons, there is a continuous search for methods whereby these hydrocarbons may be converted to more valuable materials. Among the more valuable materials which may be produced from paraffins are olefin and aromatic hydrocarbons. Thermal cracking of paraflin hydrocarbons is one of the well known and widely used processes whereby the parafiins are converted to more valuable olefinic hydrocarbons. In addition to the olefinic hydrocarbons, a very small amount of aromatic hydrocarbons are usually produced by the thermal cracking of parafiins. However, the amount of aromatic hydrocarbons produced is generally so small that the value of the cracked products is not enhanced despite the higher value of the aromatic hydrocarbons. Because of the high value of the aromatics, the greater the amount of such hydrocarbons which can be produced from the thermal cracking of paraffins the greater the value of the cracked product. I

" It is an object of the present invention to provide a new and improved process for the thermal cracking of parafiin hydrocarbons. Another object of the present invention is to provide a process for the thermal cracking of paraflin hydrocarbons whereby the quantity of aromatic hydrocarbons produced is significantly increased. Still another object of the present invention is to provide a process for the production of aromatic hydrocarbons from paraffinic hydrocarbons. Additionalobjects will become apparent from the following description of the invention herein disclosed.

In fulfillment of these and other objects, it has been found that when paraflinic hydrocarbons are subjected to thermal cracking in the presence of an organic halide there is a substantial increase in the yield of aromatic hydrocarbons. The thermal cracking may be carried out under any conditions of temperature and pressure conventional to such processes. Most often the temperature is within the range of 400 to 900 C. with temperatures of from 500 to 800 C. being preferred. The pressure is ordinarily within the range of from atmospheric to 1000 p.s.-i.g., but preferably within the range of 5 to 300 p.s.i.g. Generally, the thermal cracking of paraffin hydrocarbons is carried out in the presence of an inert diluent, preferably steam. When an inert diluent is used, it generally is used in an amount of 0.1 to 2.0 parts by weight of diluent per part by Weight of hydrocarbon feed. Preferably, a diluent to hydrocarbon weight ratio of 0.2:1 to 08:1 is used in the present invention.

The organic halides which are operable in the present invention include virtually all of such compounds. Any limitation of the scope of the term is based on practicality rather than operability. The organic halides include not only monohalides, but also di-halides and other polyhalides. The halogen may be chlorine, bromine, iodine or fluorine with chlorine and bromine being preferred. The organic radical of the organic halide may be any I straight-chain or branched-chain,

More particularly, the present in- Patented August 9, 1966 "ice hydrocarbon radical and may be cyclic or non-cyclic,

saturated or unsaturated, aromatic, naphthenic, paraffinic, or olefinic. Several non-limiting examples of organic halides are: 2-bromopropane, 2-chloropropane, l-iodopropane, 1- bromobutane, l-chlorobutane, 2-iodobutane, l-bromopentane, Z-bromopentane, 3-chloropentane,. 2-iodopentane, 2-bromohexane, 3-bromohexane, bromobenzene, chlorobenzene, m-dibromobenzene, o-dibromobenzene, p-dibromobenzene, iodobenzene, o-iiodotioluene, miodotoluene, p-iodotoluene, Z-iodohexane, 2-bromo-4- methylhexane, 3-chl-oroheptane, 3-bromoheptane, 2- iodohepatne, 2-bromo-4-ethylhexane, 4-bromooctane, 3- chlorooctane, 2-iodooctane, l-bromononane, 2-chlorodecane, 2-bromodecane, 2-bromo-6-methyldecane, 3,3- bromomethyldecane, 4-iodeundecane, o-chlorotoluene, m-chlorotoluene, p-chlorotoluene, o-bromotoluene, mbromotoluene, p-bromotoluene, 1,3,5,-dibromotoluene, obromo-chlorobenzene, m-bromo-chlorobenzene, p-bromochlorobenzene, 2-bromonaphthalene, ene, 1,3-dichloronaphthalene, 2-bromo-dipheny1, 2-chlorodiphenyl, 4-chlorodipheny1, cyclohexylchloride, cyclohexylbromide, carbon tetrachloride, 2-chloro-3-hexene, 2-bromo-2-penetene and 3-br-omo-4-octene. Generally, the organic radical of the organic halide will contain no greater than 10 carbon atoms. It is preferred that this organic radical of the organic halide contain no greater than 6 carbon atoms and that the organic radical be an alkyl radical. Further, it is preferred that the organic halide be a mono-halide or a di-halide. A particularly preferred group of organic halides are the alkyl halides containing no greater than 4 carbon atoms, which are mono-halides and which contain chlorine or bromine as the halogen. This preferred group of organic compounds include such compounds as the following non-limiting examples: 2-bromobutane, methylbromide, l-chloropropane, 2-bromopropane, ethylbromide, l-chlorobutane, l-bromopropane, 2-chlorobutane, etc.

The amount of organic halide useful in the present invention is ordinarily within the range of approximately 0.1 to 10 mol percent of the parafiin hydrocarbons in the feed. However, it is preferred that the amount of organic halide be within the range of from approximately 0.5 to 5 mol percent of the parafiin hydrocarbons in the feed. The feedstocks which may be processed in accordance with the present invention are paraflinic fractions containing 20 to 100% by weight of paraffin hydrocarbons. Preferably, the feedstock will be a paraflin fraction of to by Weight paraffin hydrocarbons. The parafiin hydrocarbons may be relatively low molecular weight liquids or high molecular weight waxy solids. Generally, the paraffinic hydrocarbons will have at least 6 carbon atoms and may be straight-chain or branched-chain. Several non-limiting examples of parafiinic hydrocarbons within the scope of the present invention are n-hexane, 2-methylpentane, 3-methylpentane, n-heptane, Z-methylhexane, 3- methylhexane, 2-ethylpentane, n-octane, 2-methylheptane, 2-ethylhexane, 3-methylheptane, 3-ethylhexane, n-nonane, 2,2-dimethylheptane, 2-methyl-4-ethylhexane, 3,3-diethylpentane, n-decane, and the like on up to and including nand iso-paraifins of 70 carbon atoms and higher. The preferred paraffin hydrocarbons are those containing 6 to 40 carbon atoms and are either straight-chain or branched-chain. In paraffin fractions containing less than 100% parafiin hydrocarbons of at least 6 carbon atoms, the impurities may include hydrocarbons such as paraffins of less than 6 carbon atoms, olefins, aromatics, naphthenes and the like as well as diluent or inert materials.

In carrying out the practice of the present invention, space velocities of 0.5 to 10 parts by volume of feed per volume of internal reaction space generally will be used.

l-chloronaphthalcarbons.

However, it is preferred that the space velocity be within the range of 2 to 6 parts by volume of paraffinic feed per volume of internal reaction space.

In order to demonstrate the eflicacy of the present invention, the following examples are presented.

Example I The paratfinic feed stock used in this demonstration was a 100% paraflinic material having a molecular weight range of 50 to 700. This paraflinic feed was passed through 35 feet of /8 inch stainless steel pipe at a rate of 4.6 pounds of feed per hour. The paraflinic feed was passed into the reaction tube concurrently with steam in a ratio of 0.37 pounds of steam per pound of feed. One mol percent af 2-bromopropane was introduced concurrently with the parafiinic feed and steam. The inlet temperature of the 35 foot reaction tube was approximately 450 C. and the exit temperature 602 C. A conversion of 87.5% was obtained. A C -C fraction was obtained from the cracked oil product by distillation. This cut represented 13.5% by weight of the total product and was found to contain 8.9% by weight of aromatic hydro- Example 11 Example I was substantially repeated with the exception that mol percent of 2-bromopropane was used. Conversion was approximately 86.1%. A C -C fraction was obtained from the cracked oil product by distillation. This fraction represented 21.8% by weight of the total cracked oil product and was found to contain 3.7% by weight of aromatic hydrocarbons.

Example III Example I was substantially repeated with the exception that the feed rate was 4.55 pounds per hour, a pressure of approximately 11.3 p.s.i.g. was used and, most important, no organic halide was added to the reaction. Conversion was approximately 73.1%. The cracked oil product was fractionated to obtain a C -C fraction and a C -C fraction. The first fraction represented 10.6% by weight of the total cracked oil product and was found to contain 0.8% by weight of aromatic hydrocarbons. The C to C fraction represented 16.5% by weight of the total cracked oil product and was found to contain 0.3% by weight of aromatic hydrocarbons.

From the above examples, it is quite apparent that the present invention produces substantially increased yields of aromatic hydrocarbons. that in both instances in which an organic halide was used that significantly improved conversion of parafiinic hydrocarbons to cracked products was obtained.

The equipment which may be used in carrying out the present invention is not critical. Any conventional thermal cracking equipment may be used. It is only necessary that the equipment be such as to withstand the pressures and temperatures of the reactions and that the equipment follow good engineering principles.

What is claimed is:

1. A process which comprises introducing a hydrocarbon feed comprised of to by weight of parafiinic hydrocarbons of 6 to 40 carbon atoms into a non-catalytic thermal reaction zone at a temperature of 500 to 800 C. and at a pressure of from atmospheric to 300 p.s.i.g. concurrently with from 0.1 to 2.0 parts by weight of steam per part by weight of hydrocarbon feed and approximately 0.1 to 10 mole percent of an alkyl halide.

2. The process of claim 1 wherein the alkyl halide is one containing no greater than 10 carbon atoms in the alkyl radical.

3. The process of claim 1 wherein the alkyl halide is selected from the group consisting of mono-chlorides, dichlorides, mono-bromides, and di-bromides.

4. The process of claim 1 wherein the steam is present in an amount of from 0.2 to 0.8 part by weight of diluent per part by weight of hydrocarbon feed.

5. The process of claim 1 wherein the alkyl halide is one containing no greater than 6 carbon atoms and selected from the group consisting of alkyl chlorides and alkyl bromides.

References Cited by the Examiner UNITED STATES PATENTS 1,826,787 10/1931 Howlett 208- 2,135,332 1l/193-8 Gary 208 2,380,958 8/1945 Folkins 208-1 15 2,402,034 6/ 1946 Folkins 2081 15 2,411,200 11/1946 Folkins 208-115 2,413,407 12/1946 Dreyfus 208--130 2,441,142 5/1948 Folkins 208--l15 2,443,497 6/ 1948 Folkins .2081l5 2,498,883 2/ 1950 Folkins 2081 15 3,065,165 1l/1962 Amis et al 208-115 DELBERT E. GANTZ, Primary Examiner.

Further, it should be noted 1 DANIEL E. WYMAN, Examiner. P. P. GARVIN, H. LEVINE, Assistant Examiners. 

1. A PROCESS WHICH COMPRISES INTRODUCING A HYDROCARBON FEED COMPRISED OF 90 TO 100% BY WEIGHT OF PARAFFINIC HYDROCARBONS OF 6 TO 40 CARBON ATOMS INTO A NON-CATALYTIC THERMAL REACTION ZONE AT A TEMPERATURE OF 500 TO 800* C. AND AT A PRESSURE OF FROM ATMOSPHERIC TO 300 P.S.I. CONCURRENTLY WITH FROM 0.1 TO 2.0 PARTS BY WEIGHT OF STEAM PER PART BY WEIGHT OF HYDROCARBON FEED AND APPROXIMMATELY 0.1 TO 10 MOLE PERCENT OF AN ALKYL HALIDE. 